wpf-calculator/SimpleCalculator/CalculatorMV.cs

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;

namespace SimpleCalculator;

public partial class CalculatorMV : ObservableObject {

    private enum State
    {
        Number,
        Action,
        Calculate,
    }

    private enum Action {
        None,
        Add,
        Subtract,
        Multiply,
        Divide,
    }

    private State currentState = State.Number;
    private string accumulator = "0";
    private (Action, string) currentAction = (Action.None, "0");
    private bool isDecimal = false;
    private bool isNegative = false;


    [ObservableProperty]
    private string resultText = "0";


    [RelayCommand]
    private void numberClicked(string value) {
        if (this.currentState == State.Action) {
            this.ResultText = "0";

        }
        if (value == "0" && this.ResultText == "0")
            return;
        if (this.ResultText == "0")
            this.ResultText = "";
        else if (this.ResultText == "-0")
            this.ResultText = "-";
        this.currentState = State.Number;
        this.ResultText += value;
    }

    [RelayCommand]
    private void acClicked() {
        this.accumulator = "";
        this.currentState = State.Number;
        this.currentAction = (Action.None, "");
        this.isDecimal = false;
        this.isNegative = false;
        this.ResultText = "0";
    }

    [RelayCommand]
    private void invertClicked() {
        if (this.isNegative) {
            this.isNegative = false;
            this.ResultText = this.ResultText.Substring(1);
        } else {
            this.isNegative = true;
            this.ResultText = "-" + this.ResultText;

        }
    }

    [RelayCommand]
    private void percentileClicked() {
        this.accumulator = this.ResultText;
        this.accumulator = (double.Parse(this.accumulator) * 0.01).ToString();
        this.ResultText = this.accumulator;
    }

    [RelayCommand]
    private void divideClicked() {
        var value = this.ResultText;
        this.currentAction = (Action.Divide, value);
        this.accumulator = "0";
        this.currentState = State.Action;
    }

    [RelayCommand]
    private void multiplyClicked() {
        var value =this.ResultText;
        this.currentAction = (Action.Multiply, value);
        this.accumulator = "0";
        this.currentState = State.Action;
    }

    [RelayCommand]
    private void subtractClicked() {
        var value = this.ResultText;
        this.currentAction = (Action.Subtract, value);
        this.accumulator = "0";
        this.currentState = State.Action;
    }

    [RelayCommand]
    private void addClicked() {
        var value = this.ResultText;
        this.currentAction = (Action.Add, value);
        this.accumulator = "0";
        this.currentState = State.Action;
    }

    [RelayCommand]
    private void equalClicked() {
        var (action, value) = this.currentAction;
        switch (action) {
            case Action.None:
                break;
            case Action.Add:
                this.accumulator = (double.Parse(value) + double.Parse(this.ResultText)).ToString();
                break;
            case Action.Subtract:
                this.accumulator = (double.Parse(value) - double.Parse(this.ResultText)).ToString();
                break;
            case Action.Multiply: 
                this.accumulator = (double.Parse(value) * double.Parse(this.ResultText)).ToString();
                break;
            case Action.Divide:
                this.accumulator = (double.Parse(value) / double.Parse(this.ResultText)).ToString();
                break;
        }
        this.ResultText = this.accumulator.ToString();
        this.currentState = State.Calculate;
    }

    [RelayCommand]
    private void decimalPointClicked() {
        this.isDecimal = true;
        this.ResultText += ",";
    }

}